How to check the public IP address of a connection using curl command line

The Challenge of Discovering External IPs Without a Graphical Interface

When administering remote servers or distant computers through a pure text connection like SSH (which allows secure remote access to another computer), we often need to know our public IP address. The public IP address is like your street address and postal code on the vast internet network, allowing other computers to know exactly where to find us. Local computers connected to home or corporate routers usually use private internal addresses, which cannot be used for direct connections originating from the open internet.

Discovering this external number might seem simple in a visual web browser, but it becomes a puzzle when we only have a black command-line screen. At such moments, the command line becomes our best ally, allowing us to make direct inquiries to servers scattered around the world. This is where the curl utility comes in, a standard tool on almost all modern operating systems used to transfer data using various network protocols.

Understanding the Role of the Curl Utility in Data Transmission

Curl is an extremely versatile command-line program that acts as a highly programmable digital courier. In practice, it sends HTTP requests (the fundamental protocol that transfers pages and data on the web) to a given address and brings back the response sent by the server. Instead of displaying colorful buttons or images, it shows the pure text returned by the target machine, which vastly simplifies task automation for engineers and system administrators.

When we run a curl command to any website, our machine sends a data packet that travels through cables, routers, and carriers until it reaches the destination server. That server, upon receiving our message, can look at the packet and see exactly what public IP address originated and stamped that request. The server then simply writes that address back into the HTTP response body, delivering the information on a silver platter to our terminal.

Using Echo Services to Retrieve the IP Address

There are several free and public web services designed specifically for this purpose, often known as echo services or IP reflectors. One of the most classic and simple examples to use is the service maintained by the ifconfig.me platform. In practice, if we type curl ifconfig.me in the terminal, our computer will make a quick call to that server and receive back just a single line containing our current external IP number.

curl ifconfig.me

This method works with extreme speed because echo services are designed to respond with minimal processing possible. They do not load stylesheets, images, or complex scripts; they simply read our connection header and return the raw text. Other popular and highly reliable alternatives include icanhazip.com and ident.me, which offer the same minimalist, straightforward behavior.

Ensuring Clean Responses with Specific Protocols

Sometimes modern web services try to be too smart and alter their response depending on who is asking, delivering full HTML pages instead of pure text. To prevent curl from receiving unnecessary markup code and bringing unwanted tags into our terminal, we can force specific protocol versions or direct queries to specialized endpoints. For example, many services offer dedicated URLs that guarantee exclusive delivery of the IP in plain text format.

Another useful strategy involves utilizing additional parameters of curl itself to control the request behavior. The -s parameter (which stands for silent) hides the progress bar and error messages that the program usually displays on screen, leaving the output clean with only the final result. Combining this option with the correct address ensures that manual checks or scripts run without visual clutter in the terminal.

curl -s icanhazip.com

Automating Data Extraction in Network Scripts

In software engineering and infrastructure operations, we rarely use commands just to read information on a screen; we usually want a script to make decisions based on that data. If we need an automation program to adjust firewall rules or log dynamic IP changes, we need the curl command output to be handled cleanly, without excessive line breaks or unwanted whitespace.

To achieve this surgical precision, we can combine curl with text processing tools like awk or tr, although for most minimalist IP services this is unnecessary. A common automation example involves storing the result directly into an operating system environment variable, allowing backup or monitoring scripts to utilize this IP address immediately after the query.

PUBLIC_IP=$(curl -s icanhazip.com) && echo